IDL doesn't pick up headlights - anything that subtends a small angle is a tiny contributer. Remember, diffuse light from any given point came from a hemisphere visible from that point. A headlight even from a few feet away is nothing - barely contributes.

This is not proper math, but tolerate me for a moment. The world around any given point (visible hemisphere) can be thought of as 90 degrees by 360 degrees. In "square degrees"  that's roughly 90 * 360 or something like 32000 units of environment.

A nearby headlight might be roughly 8 by 8 or 64 units.

So the headlight occupies 64 / 32000 = .002 of the environment units that contribute to IDL. Is it any wonder then that the intensity of light from a glowing headlight prop is practically nothing?

You need focused, directed beams in this equation. I would add spotlights to perform that function. But I was merely trying out the fog on the neon undercarriage.

 

Meanwhile, my render was 5 minutes. Did you change my settings on the prop? I made sure to make it invisible to raytracing and not a light emitter. It's way too many transparencies for the raytrace engine to deal with.

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Renderosity forum reply notifications are wonky. If I read a follow-up in a thread, but I don't myself reply, then notifications no longer happen AT ALL on that thread. So if I seem to be ignoring a question, that's why. (Updated September 23, 2019)